We are adopting a new airworthiness directive (AD) for all Burl A. Rogers (type certificate previously held by William Brad Mitchell and Aeronca, Inc.) Models 15AC and S15AC airplanes. This AD was prompted by reports of intergranular exfoliation and corrosion of the upper and/or lower wing main spar cap angles found on the affected airplanes. This AD requires repetitive inspections of the upper and lower main wing spar cap angles for cracks and/or corrosion and installing inspection access panels. This AD also requires replacing the wing spar cap angles if moderate or severe corrosion is found and applying corrosion inhibitor. We are issuing this AD to correct the unsafe condition on these products.

You may examine the AD docket on the Internet at http://www.regulations.gov; or in person at the Docket Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this AD, the regulatory evaluation, any comments received, and other information. The address for the Docket Office (phone: 800-647-5527) is Document Management Facility, U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE., Washington, DC 20590.

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that would apply to the specified products. That NPRM published in the Federal Register on April 4, 2011 (76 FR 18454). That NPRM proposed to require repetitive inspections of the upper and lower main wing spar cap angles for cracks and/or corrosion and installing inspection access panels. That NPRM also proposed to require replacing the wing spar cap angles if moderate or severe corrosion is found and applying corrosion inhibitor.

We gave the public the opportunity to participate in developing this AD. The following presents the comments received on the proposal (76 FR 18454, April 4, 2011) and the FAA's response to each comment.

The commenters stated that additional time was needed to receive all of the data requested through the Freedom of Information Act and to prepare a request for an alternative method of compliance (AMOC).

We do not agree to extend the comment period again. We issued the proposed AD (76 FR 18454, April 4, 2011) with a 45-day open comment period. Due to several public comments received at that time requesting an extension of the comment period to facilitate fact finding/information gathering, we issued an extension of the comment period (76 FR 23920, April 29, 2011) that extended the comment period for an additional 45 days. Even though we did not extend the comment period any further, we have accepted all comments to the docket that were received after the comment close date.

We have determined it is in the best interest of the public to go forward with this AD to address the unsafe condition on these airplanes. The public may always propose AMOCs to show compliance to the requirements cited in the AD. We will review and consider all AMOC requests we receive provided they follow the procedures in 14 CFR 39.19 and this AD.

The commenters stated that using a borescope when inspecting the main spar cap angles on the wings for corrosion would save time and the expense of installing access covers in the wings.

We agree that a borescope inspection could provide an acceptable level of safety for doing the required inspection; however, we disagree with approving it for this AD because we do not have written detailed guidance for doing a borescope inspection that we can refer to in this AD at this time.

The public may always propose AMOCs to show compliance to the requirements cited in the AD. We will review and consider all AMOC requests we receive provided they follow the procedures in 14 CFR 39.19 and this AD.

An anonymous commenter stated that the Costs of Compliance section should be re-evaluated.

The commenter stated that the estimated cost information in the proposed AD (76 FR 18454, April 4, 2011) is misleading since some of the information is presented per wing instead of per airplane. The commenter also stated that the estimated cost of replacing the main spar cap on both wings could exceed the value of the airplane, and the estimated cost to inspect and install inspection panels could easily amount to 10 to 25 percent of the value of the airplane.

The commenter stated that there are less costly, yet as effective, options to comply with the AD, and we should include those costs in the AD.

We do not agree with the commenter. We determined that the estimated costs stated in the proposed AD (76 FR 18454, April 4, 2011) represent the most accurate estimate we can make at this time. Total fleet repair costs were not calculated because we have no way of determining the number of wings that will be found to be corroded and/or cracked that will need to be replaced.

The public may always propose AMOCs to show compliance to the requirements cited in the AD. The FAA will review and consider all AMOC requests we receive provided they follow the procedures in 14 CFR 39.19 and this AD.

Burl's Aircraft, LLC issued additional installation instructions for installing the 2-1272 reinforcement doubler and the 2-1285 inspection cover assemblies. We infer that Burl's Aircraft, LLC wants the FAA to include the installation instructions into the final rule AD action.

We agree. We have revised the final rule AD action to incorporate using the installation instructions.

We reviewed the relevant data, considered the comments received, and determined that air safety and the public interest require adopting the AD with the change described previously and minor editorial changes. We have determined that these minor changes:

• Are consistent with the intent that was proposed in the NPRM (76 FR 18454, April 4, 2011) for correcting the unsafe condition; and

• Do not add any additional burden upon the public than was already proposed in the NPRM (76 FR 18454, April 4, 2011).

We also determined that these changes will not increase the economicburden on any operator or increase the scope of the AD.

We estimate the following costs to do any necessary replacements that will be required based on the results of the inspections. We have no way of determining the number of aircraft that might need these replacements:

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII: Aviation Programs, describes in more detail the scope of the Agency's authority.

We are issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701: “General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

This AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government.

For the reasons discussed above, I certify that this AD:

(1) Is not a “significant regulatory action” under Executive Order 12866,

(2) Is not a “significant rule” under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979),

(3) Will not affect intrastate aviation in Alaska, and

(4) Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.

This AD applies to Burl A. Rogers (type certificate previously held by William Brad Mitchell and Aeronca, Inc.) Model 15AC and S15AC airplanes, all serial numbers, that are certificated in any category.

This AD was prompted by reports of intergranular exfoliation and corrosion of the upper and/or lower wing main spar cap angles found on the affected airplanes. We are issuing this AD to detect and correct cracks and corrosion in the wing main spar cap angles, which could result in reduced strength of the wing spar and the load carrying capacity of the wing. This could lead to wing failure and consequent loss of control.

Comply with this AD within the compliance times specified, unless already done (does not eliminate the repetitive actions of this AD).

What must be done?

When must it be done?

How must it be done?

(1) Inspect the exposed trailing edges of both the upper and lower main spar cap angles on both the left and right wing for signs of cracks, intergranular exfoliation, and corrosion

(i) Within the next 25 hours time-in-service (TIS) after April 17, 2012 (the effective date of this AD) or within the next 6 months after April 17, 2012 (the effective date of this AD), whichever occurs first; or(ii)If the left and/or right wing have been repaired and both the upper and lower main spar caps have been replaced using new parts: Inspect at or before the next annual inspection that occurs 10 years after the replacement or within the next 100 hours TIS after April 17, 2012 (the effective date of this AD), whichever occurs later. This compliance time applies separately to each wing

(2) After completing the inspection required in paragraph (f)(1) of this AD, install new inspection hole skin reinforcement doublers and the associated screw cover plate in both the left and right wing

(i) Within 12 months after April 17, 2012 (the effective date of this AD); or(ii)If the left and/or right wing have been repaired and both the upper and lower main spar caps have been replaced using new parts: At or before the next annual inspection that occurs 10 years after the replacement or within the next 100 hours TIS after April 17, 2012 (the effective date of this AD), whichever occurs later. This compliance time applies separately to each wing

(3) After completing the inspection required in paragraph (f)(1) of this AD and installing the new inspection hole skin reinforcement doublers in the left and right wing as required in paragraph (f)(2) of this AD, through the inspection access panels, inspect the leading and trailing edges of both the upper and lower main spar cap angles on both the left and right wing for signs of cracks, intergranular exfoliation and corrosion

Before further flight after installing the inspection hole skin reinforcement doublers as required in paragraph (f)(2) of this AD

(4) Remove any light corrosion found during the inspection required in paragraph (f)(3) of this AD and treat the entirety of both the upper and lower main spar cap angles on both the left and right wing with corrosion inhibitor

Before further flight after the inspection required in paragraph (f)(3) of this AD

(5) If cracks, intergranular exfoliation, or moderate or severe corrosion is found during the inspection required in paragraphs (f)(1) or (f)(3) of this AD, replace the affected main spar cap angles in their entirety as a single piece. Splicing of the main spar cap angles is not permitted

Before further flight after the inspection required in paragraphs (f)(1) and (f)(3) of this AD

(6) Removing the wing inspection access panels, repetitively inspect both the upper and lower forward main spar caps on both the left and right wing for signs of cracks, intergranular exfoliation, and corrosion

Repetitively thereafter at intervals not to exceed every 12 months after the inspection required in paragraph (f)(3) of this AD

(8) After each inspection required in paragraph (f)(6) of this AD, if cracks, intergranular exfoliation, or moderate or severe corrosion is found, replace the affected main spar cap angles in their entirety as a single piece. Splicing of the main spar cap angles is not permitted

Before further flight after each inspection required in paragraph (f)(6) of this AD. Continue with the repetitive inspections required in paragraph (f)(6) of this AD

(1) The Manager, Anchorage Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of the ACO, send it to the attention of the person identified in the Related Information section of this AD.

(2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/certificate holding district office.

(1) You must use the following service information to do the actions required by this AD, unless the AD specifies otherwise. The Director of the Federal Register approved the incorporation by reference (IBR) under 5 U.S.C. 552(a) and 1 CFR part 51.

(3) You may review copies of the service information at the FAA, Small Airplane Directorate, 901 Locust, Room 301, Kansas City, MO 64106. For information on the availability of this material at the FAA, call (816) 329-4148.